2 * af_can.c - Protocol family CAN core module
3 * (used by different CAN protocol modules)
5 * Copyright (c) 2002-2007 Volkswagen Group Electronic Research
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of Volkswagen nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
20 * Alternatively, provided that this notice is retained in full, this
21 * software may be distributed under the terms of the GNU General
22 * Public License ("GPL") version 2, in which case the provisions of the
23 * GPL apply INSTEAD OF those given above.
25 * The provided data structures and external interfaces from this code
26 * are not restricted to be used by modules with a GPL compatible license.
28 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
29 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
30 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
31 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
32 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
33 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
34 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
38 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
41 * Send feedback to <socketcan-users@lists.berlios.de>
45 #include <linux/module.h>
46 #include <linux/init.h>
47 #include <linux/kmod.h>
48 #include <linux/slab.h>
49 #include <linux/list.h>
50 #include <linux/spinlock.h>
51 #include <linux/rcupdate.h>
52 #include <linux/uaccess.h>
53 #include <linux/net.h>
54 #include <linux/netdevice.h>
55 #include <linux/socket.h>
56 #include <linux/if_ether.h>
57 #include <linux/if_arp.h>
58 #include <linux/skbuff.h>
59 #include <linux/can.h>
60 #include <linux/can/core.h>
61 #include <net/net_namespace.h>
66 static __initdata const char banner[] = KERN_INFO
67 "can: controller area network core (" CAN_VERSION_STRING ")\n";
69 MODULE_DESCRIPTION("Controller Area Network PF_CAN core");
70 MODULE_LICENSE("Dual BSD/GPL");
71 MODULE_AUTHOR("Urs Thuermann <urs.thuermann@volkswagen.de>, "
72 "Oliver Hartkopp <oliver.hartkopp@volkswagen.de>");
74 MODULE_ALIAS_NETPROTO(PF_CAN);
76 static int stats_timer __read_mostly = 1;
77 module_param(stats_timer, int, S_IRUGO);
78 MODULE_PARM_DESC(stats_timer, "enable timer for statistics (default:on)");
80 HLIST_HEAD(can_rx_dev_list);
81 static struct dev_rcv_lists can_rx_alldev_list;
82 static DEFINE_SPINLOCK(can_rcvlists_lock);
84 static struct kmem_cache *rcv_cache __read_mostly;
86 /* table of registered CAN protocols */
87 static struct can_proto *proto_tab[CAN_NPROTO] __read_mostly;
88 static DEFINE_SPINLOCK(proto_tab_lock);
90 struct timer_list can_stattimer; /* timer for statistics update */
91 struct s_stats can_stats; /* packet statistics */
92 struct s_pstats can_pstats; /* receive list statistics */
95 * af_can socket functions
98 static int can_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
100 struct sock *sk = sock->sk;
105 return sock_get_timestamp(sk, (struct timeval __user *)arg);
112 static void can_sock_destruct(struct sock *sk)
114 skb_queue_purge(&sk->sk_receive_queue);
117 static int can_create(struct net *net, struct socket *sock, int protocol)
120 struct can_proto *cp;
123 sock->state = SS_UNCONNECTED;
125 if (protocol < 0 || protocol >= CAN_NPROTO)
128 if (net != &init_net)
129 return -EAFNOSUPPORT;
131 #ifdef CONFIG_MODULES
132 /* try to load protocol module kernel is modular */
133 if (!proto_tab[protocol]) {
134 err = request_module("can-proto-%d", protocol);
137 * In case of error we only print a message but don't
138 * return the error code immediately. Below we will
139 * return -EPROTONOSUPPORT
141 if (err && printk_ratelimit())
142 printk(KERN_ERR "can: request_module "
143 "(can-proto-%d) failed.\n", protocol);
147 spin_lock(&proto_tab_lock);
148 cp = proto_tab[protocol];
149 if (cp && !try_module_get(cp->prot->owner))
151 spin_unlock(&proto_tab_lock);
153 /* check for available protocol and correct usage */
156 return -EPROTONOSUPPORT;
158 if (cp->type != sock->type) {
159 err = -EPROTONOSUPPORT;
165 sk = sk_alloc(net, PF_CAN, GFP_KERNEL, cp->prot);
171 sock_init_data(sock, sk);
172 sk->sk_destruct = can_sock_destruct;
174 if (sk->sk_prot->init)
175 err = sk->sk_prot->init(sk);
178 /* release sk on errors */
184 module_put(cp->prot->owner);
193 * can_send - transmit a CAN frame (optional with local loopback)
194 * @skb: pointer to socket buffer with CAN frame in data section
195 * @loop: loopback for listeners on local CAN sockets (recommended default!)
197 * Due to the loopback this routine must not be called from hardirq context.
201 * -ENETDOWN when the selected interface is down
202 * -ENOBUFS on full driver queue (see net_xmit_errno())
203 * -ENOMEM when local loopback failed at calling skb_clone()
204 * -EPERM when trying to send on a non-CAN interface
205 * -EINVAL when the skb->data does not contain a valid CAN frame
207 int can_send(struct sk_buff *skb, int loop)
209 struct sk_buff *newskb = NULL;
210 struct can_frame *cf = (struct can_frame *)skb->data;
213 if (skb->len != sizeof(struct can_frame) || cf->can_dlc > 8) {
218 if (skb->dev->type != ARPHRD_CAN) {
223 if (!(skb->dev->flags & IFF_UP)) {
228 skb->protocol = htons(ETH_P_CAN);
229 skb_reset_network_header(skb);
230 skb_reset_transport_header(skb);
233 /* local loopback of sent CAN frames */
235 /* indication for the CAN driver: do loopback */
236 skb->pkt_type = PACKET_LOOPBACK;
239 * The reference to the originating sock may be required
240 * by the receiving socket to check whether the frame is
241 * its own. Example: can_raw sockopt CAN_RAW_RECV_OWN_MSGS
242 * Therefore we have to ensure that skb->sk remains the
243 * reference to the originating sock by restoring skb->sk
244 * after each skb_clone() or skb_orphan() usage.
247 if (!(skb->dev->flags & IFF_ECHO)) {
249 * If the interface is not capable to do loopback
250 * itself, we do it here.
252 newskb = skb_clone(skb, GFP_ATOMIC);
258 newskb->sk = skb->sk;
259 newskb->ip_summed = CHECKSUM_UNNECESSARY;
260 newskb->pkt_type = PACKET_BROADCAST;
263 /* indication for the CAN driver: no loopback required */
264 skb->pkt_type = PACKET_HOST;
267 /* send to netdevice */
268 err = dev_queue_xmit(skb);
270 err = net_xmit_errno(err);
280 /* update statistics */
281 can_stats.tx_frames++;
282 can_stats.tx_frames_delta++;
286 EXPORT_SYMBOL(can_send);
292 static struct dev_rcv_lists *find_dev_rcv_lists(struct net_device *dev)
294 struct dev_rcv_lists *d = NULL;
295 struct hlist_node *n;
298 * find receive list for this device
300 * The hlist_for_each_entry*() macros curse through the list
301 * using the pointer variable n and set d to the containing
302 * struct in each list iteration. Therefore, after list
303 * iteration, d is unmodified when the list is empty, and it
304 * points to last list element, when the list is non-empty
305 * but no match in the loop body is found. I.e. d is *not*
306 * NULL when no match is found. We can, however, use the
307 * cursor variable n to decide if a match was found.
310 hlist_for_each_entry_rcu(d, n, &can_rx_dev_list, list) {
319 * find_rcv_list - determine optimal filterlist inside device filter struct
320 * @can_id: pointer to CAN identifier of a given can_filter
321 * @mask: pointer to CAN mask of a given can_filter
322 * @d: pointer to the device filter struct
325 * Returns the optimal filterlist to reduce the filter handling in the
326 * receive path. This function is called by service functions that need
327 * to register or unregister a can_filter in the filter lists.
329 * A filter matches in general, when
331 * <received_can_id> & mask == can_id & mask
333 * so every bit set in the mask (even CAN_EFF_FLAG, CAN_RTR_FLAG) describe
334 * relevant bits for the filter.
336 * The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
337 * filter for error frames (CAN_ERR_FLAG bit set in mask). For error frames
338 * there is a special filterlist and a special rx path filter handling.
341 * Pointer to optimal filterlist for the given can_id/mask pair.
342 * Constistency checked mask.
343 * Reduced can_id to have a preprocessed filter compare value.
345 static struct hlist_head *find_rcv_list(canid_t *can_id, canid_t *mask,
346 struct dev_rcv_lists *d)
348 canid_t inv = *can_id & CAN_INV_FILTER; /* save flag before masking */
350 /* filter for error frames in extra filterlist */
351 if (*mask & CAN_ERR_FLAG) {
352 /* clear CAN_ERR_FLAG in filter entry */
353 *mask &= CAN_ERR_MASK;
354 return &d->rx[RX_ERR];
357 /* with cleared CAN_ERR_FLAG we have a simple mask/value filterpair */
359 #define CAN_EFF_RTR_FLAGS (CAN_EFF_FLAG | CAN_RTR_FLAG)
361 /* ensure valid values in can_mask for 'SFF only' frame filtering */
362 if ((*mask & CAN_EFF_FLAG) && !(*can_id & CAN_EFF_FLAG))
363 *mask &= (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS);
365 /* reduce condition testing at receive time */
368 /* inverse can_id/can_mask filter */
370 return &d->rx[RX_INV];
372 /* mask == 0 => no condition testing at receive time */
374 return &d->rx[RX_ALL];
376 /* extra filterlists for the subscription of a single non-RTR can_id */
377 if (((*mask & CAN_EFF_RTR_FLAGS) == CAN_EFF_RTR_FLAGS)
378 && !(*can_id & CAN_RTR_FLAG)) {
380 if (*can_id & CAN_EFF_FLAG) {
381 if (*mask == (CAN_EFF_MASK | CAN_EFF_RTR_FLAGS)) {
382 /* RFC: a future use-case for hash-tables? */
383 return &d->rx[RX_EFF];
386 if (*mask == (CAN_SFF_MASK | CAN_EFF_RTR_FLAGS))
387 return &d->rx_sff[*can_id];
391 /* default: filter via can_id/can_mask */
392 return &d->rx[RX_FIL];
396 * can_rx_register - subscribe CAN frames from a specific interface
397 * @dev: pointer to netdevice (NULL => subcribe from 'all' CAN devices list)
398 * @can_id: CAN identifier (see description)
399 * @mask: CAN mask (see description)
400 * @func: callback function on filter match
401 * @data: returned parameter for callback function
402 * @ident: string for calling module indentification
405 * Invokes the callback function with the received sk_buff and the given
406 * parameter 'data' on a matching receive filter. A filter matches, when
408 * <received_can_id> & mask == can_id & mask
410 * The filter can be inverted (CAN_INV_FILTER bit set in can_id) or it can
411 * filter for error frames (CAN_ERR_FLAG bit set in mask).
413 * The provided pointer to the sk_buff is guaranteed to be valid as long as
414 * the callback function is running. The callback function must *not* free
415 * the given sk_buff while processing it's task. When the given sk_buff is
416 * needed after the end of the callback function it must be cloned inside
417 * the callback function with skb_clone().
421 * -ENOMEM on missing cache mem to create subscription entry
422 * -ENODEV unknown device
424 int can_rx_register(struct net_device *dev, canid_t can_id, canid_t mask,
425 void (*func)(struct sk_buff *, void *), void *data,
429 struct hlist_head *rl;
430 struct dev_rcv_lists *d;
433 /* insert new receiver (dev,canid,mask) -> (func,data) */
435 r = kmem_cache_alloc(rcv_cache, GFP_KERNEL);
439 spin_lock(&can_rcvlists_lock);
441 d = find_dev_rcv_lists(dev);
443 rl = find_rcv_list(&can_id, &mask, d);
452 hlist_add_head_rcu(&r->list, rl);
455 can_pstats.rcv_entries++;
456 if (can_pstats.rcv_entries_max < can_pstats.rcv_entries)
457 can_pstats.rcv_entries_max = can_pstats.rcv_entries;
459 kmem_cache_free(rcv_cache, r);
463 spin_unlock(&can_rcvlists_lock);
467 EXPORT_SYMBOL(can_rx_register);
470 * can_rx_delete_device - rcu callback for dev_rcv_lists structure removal
472 static void can_rx_delete_device(struct rcu_head *rp)
474 struct dev_rcv_lists *d = container_of(rp, struct dev_rcv_lists, rcu);
480 * can_rx_delete_receiver - rcu callback for single receiver entry removal
482 static void can_rx_delete_receiver(struct rcu_head *rp)
484 struct receiver *r = container_of(rp, struct receiver, rcu);
486 kmem_cache_free(rcv_cache, r);
490 * can_rx_unregister - unsubscribe CAN frames from a specific interface
491 * @dev: pointer to netdevice (NULL => unsubcribe from 'all' CAN devices list)
492 * @can_id: CAN identifier
494 * @func: callback function on filter match
495 * @data: returned parameter for callback function
498 * Removes subscription entry depending on given (subscription) values.
500 void can_rx_unregister(struct net_device *dev, canid_t can_id, canid_t mask,
501 void (*func)(struct sk_buff *, void *), void *data)
503 struct receiver *r = NULL;
504 struct hlist_head *rl;
505 struct hlist_node *next;
506 struct dev_rcv_lists *d;
508 spin_lock(&can_rcvlists_lock);
510 d = find_dev_rcv_lists(dev);
512 printk(KERN_ERR "BUG: receive list not found for "
513 "dev %s, id %03X, mask %03X\n",
514 DNAME(dev), can_id, mask);
518 rl = find_rcv_list(&can_id, &mask, d);
521 * Search the receiver list for the item to delete. This should
522 * exist, since no receiver may be unregistered that hasn't
523 * been registered before.
526 hlist_for_each_entry_rcu(r, next, rl, list) {
527 if (r->can_id == can_id && r->mask == mask
528 && r->func == func && r->data == data)
533 * Check for bugs in CAN protocol implementations:
534 * If no matching list item was found, the list cursor variable next
535 * will be NULL, while r will point to the last item of the list.
539 printk(KERN_ERR "BUG: receive list entry not found for "
540 "dev %s, id %03X, mask %03X\n",
541 DNAME(dev), can_id, mask);
547 hlist_del_rcu(&r->list);
550 if (can_pstats.rcv_entries > 0)
551 can_pstats.rcv_entries--;
553 /* remove device structure requested by NETDEV_UNREGISTER */
554 if (d->remove_on_zero_entries && !d->entries)
555 hlist_del_rcu(&d->list);
560 spin_unlock(&can_rcvlists_lock);
562 /* schedule the receiver item for deletion */
564 call_rcu(&r->rcu, can_rx_delete_receiver);
566 /* schedule the device structure for deletion */
568 call_rcu(&d->rcu, can_rx_delete_device);
570 EXPORT_SYMBOL(can_rx_unregister);
572 static inline void deliver(struct sk_buff *skb, struct receiver *r)
574 r->func(skb, r->data);
578 static int can_rcv_filter(struct dev_rcv_lists *d, struct sk_buff *skb)
581 struct hlist_node *n;
583 struct can_frame *cf = (struct can_frame *)skb->data;
584 canid_t can_id = cf->can_id;
589 if (can_id & CAN_ERR_FLAG) {
590 /* check for error frame entries only */
591 hlist_for_each_entry_rcu(r, n, &d->rx[RX_ERR], list) {
592 if (can_id & r->mask) {
600 /* check for unfiltered entries */
601 hlist_for_each_entry_rcu(r, n, &d->rx[RX_ALL], list) {
606 /* check for can_id/mask entries */
607 hlist_for_each_entry_rcu(r, n, &d->rx[RX_FIL], list) {
608 if ((can_id & r->mask) == r->can_id) {
614 /* check for inverted can_id/mask entries */
615 hlist_for_each_entry_rcu(r, n, &d->rx[RX_INV], list) {
616 if ((can_id & r->mask) != r->can_id) {
622 /* check filterlists for single non-RTR can_ids */
623 if (can_id & CAN_RTR_FLAG)
626 if (can_id & CAN_EFF_FLAG) {
627 hlist_for_each_entry_rcu(r, n, &d->rx[RX_EFF], list) {
628 if (r->can_id == can_id) {
634 can_id &= CAN_SFF_MASK;
635 hlist_for_each_entry_rcu(r, n, &d->rx_sff[can_id], list) {
644 static int can_rcv(struct sk_buff *skb, struct net_device *dev,
645 struct packet_type *pt, struct net_device *orig_dev)
647 struct dev_rcv_lists *d;
648 struct can_frame *cf = (struct can_frame *)skb->data;
651 if (!net_eq(dev_net(dev), &init_net))
654 if (WARN_ONCE(dev->type != ARPHRD_CAN ||
655 skb->len != sizeof(struct can_frame) ||
657 "PF_CAN: dropped non conform skbuf: "
658 "dev type %d, len %d, can_dlc %d\n",
659 dev->type, skb->len, cf->can_dlc))
662 /* update statistics */
663 can_stats.rx_frames++;
664 can_stats.rx_frames_delta++;
668 /* deliver the packet to sockets listening on all devices */
669 matches = can_rcv_filter(&can_rx_alldev_list, skb);
671 /* find receive list for this device */
672 d = find_dev_rcv_lists(dev);
674 matches += can_rcv_filter(d, skb);
678 /* consume the skbuff allocated by the netdevice driver */
683 can_stats.matches_delta++;
686 return NET_RX_SUCCESS;
694 * af_can protocol functions
698 * can_proto_register - register CAN transport protocol
699 * @cp: pointer to CAN protocol structure
703 * -EINVAL invalid (out of range) protocol number
704 * -EBUSY protocol already in use
705 * -ENOBUF if proto_register() fails
707 int can_proto_register(struct can_proto *cp)
709 int proto = cp->protocol;
712 if (proto < 0 || proto >= CAN_NPROTO) {
713 printk(KERN_ERR "can: protocol number %d out of range\n",
718 err = proto_register(cp->prot, 0);
722 spin_lock(&proto_tab_lock);
723 if (proto_tab[proto]) {
724 printk(KERN_ERR "can: protocol %d already registered\n",
728 proto_tab[proto] = cp;
730 /* use generic ioctl function if not defined by module */
732 cp->ops->ioctl = can_ioctl;
734 spin_unlock(&proto_tab_lock);
737 proto_unregister(cp->prot);
741 EXPORT_SYMBOL(can_proto_register);
744 * can_proto_unregister - unregister CAN transport protocol
745 * @cp: pointer to CAN protocol structure
747 void can_proto_unregister(struct can_proto *cp)
749 int proto = cp->protocol;
751 spin_lock(&proto_tab_lock);
752 if (!proto_tab[proto]) {
753 printk(KERN_ERR "BUG: can: protocol %d is not registered\n",
756 proto_tab[proto] = NULL;
757 spin_unlock(&proto_tab_lock);
759 proto_unregister(cp->prot);
761 EXPORT_SYMBOL(can_proto_unregister);
764 * af_can notifier to create/remove CAN netdevice specific structs
766 static int can_notifier(struct notifier_block *nb, unsigned long msg,
769 struct net_device *dev = (struct net_device *)data;
770 struct dev_rcv_lists *d;
772 if (!net_eq(dev_net(dev), &init_net))
775 if (dev->type != ARPHRD_CAN)
780 case NETDEV_REGISTER:
783 * create new dev_rcv_lists for this device
785 * N.B. zeroing the struct is the correct initialization
786 * for the embedded hlist_head structs.
787 * Another list type, e.g. list_head, would require
788 * explicit initialization.
791 d = kzalloc(sizeof(*d), GFP_KERNEL);
794 "can: allocation of receive list failed\n");
799 spin_lock(&can_rcvlists_lock);
800 hlist_add_head_rcu(&d->list, &can_rx_dev_list);
801 spin_unlock(&can_rcvlists_lock);
805 case NETDEV_UNREGISTER:
806 spin_lock(&can_rcvlists_lock);
808 d = find_dev_rcv_lists(dev);
811 d->remove_on_zero_entries = 1;
814 hlist_del_rcu(&d->list);
816 printk(KERN_ERR "can: notifier: receive list not "
817 "found for dev %s\n", dev->name);
819 spin_unlock(&can_rcvlists_lock);
822 call_rcu(&d->rcu, can_rx_delete_device);
831 * af_can module init/exit functions
834 static struct packet_type can_packet __read_mostly = {
835 .type = cpu_to_be16(ETH_P_CAN),
840 static const struct net_proto_family can_family_ops = {
842 .create = can_create,
843 .owner = THIS_MODULE,
846 /* notifier block for netdevice event */
847 static struct notifier_block can_netdev_notifier __read_mostly = {
848 .notifier_call = can_notifier,
851 static __init int can_init(void)
855 rcv_cache = kmem_cache_create("can_receiver", sizeof(struct receiver),
861 * Insert can_rx_alldev_list for reception on all devices.
862 * This struct is zero initialized which is correct for the
863 * embedded hlist heads, the dev pointer, and the entries counter.
866 spin_lock(&can_rcvlists_lock);
867 hlist_add_head_rcu(&can_rx_alldev_list.list, &can_rx_dev_list);
868 spin_unlock(&can_rcvlists_lock);
871 /* the statistics are updated every second (timer triggered) */
872 setup_timer(&can_stattimer, can_stat_update, 0);
873 mod_timer(&can_stattimer, round_jiffies(jiffies + HZ));
875 can_stattimer.function = NULL;
879 /* protocol register */
880 sock_register(&can_family_ops);
881 register_netdevice_notifier(&can_netdev_notifier);
882 dev_add_pack(&can_packet);
887 static __exit void can_exit(void)
889 struct dev_rcv_lists *d;
890 struct hlist_node *n, *next;
893 del_timer(&can_stattimer);
897 /* protocol unregister */
898 dev_remove_pack(&can_packet);
899 unregister_netdevice_notifier(&can_netdev_notifier);
900 sock_unregister(PF_CAN);
902 /* remove can_rx_dev_list */
903 spin_lock(&can_rcvlists_lock);
904 hlist_del(&can_rx_alldev_list.list);
905 hlist_for_each_entry_safe(d, n, next, &can_rx_dev_list, list) {
909 spin_unlock(&can_rcvlists_lock);
911 rcu_barrier(); /* Wait for completion of call_rcu()'s */
913 kmem_cache_destroy(rcv_cache);
916 module_init(can_init);
917 module_exit(can_exit);